Thermoconductive silicone compositions have entered into use for the purpose of high-efficiency heat dissipation accompanying the higher densities and higher levels of integration seen in hybrid ICs and printed-circuit substrates carried by electronic components such as transistors, ICs, memory elements, and so forth. These thermoconductive silicone compositions take the form of, for example, thermoconductive silicone greases, thermoconductive silicone gel compositions, and thermoconductive silicone rubber compositions.
With the goal of improving the thermal conductivity of such thermoconductive silicone compositions containing a large amount of thermoconductive filler, for example, Japanese Laid Open (Unexamined or Kokai or A) Patent Application Number 2000-256558 discloses a thermoconductive silicone rubber composition comprising an organopolysiloxane, hydrolyzable group-functional methylpolysiloxane, thermoconductive filler, and curing agent. Japanese Laid Open (Unexamined or Kokai or A) Patent Application Number 2001-139815 discloses a thermoconductive silicone rubber composition comprising a curable organopolysiloxane, curing agent, and thermoconductive filler whose surface has been treated with oligosiloxane bearing Si-bonded alkoxy.
However, when these thermoconductive silicone compositions are subjected to still loaded with an even larger amount of thermoconductive filler, e.g., alumina, to raise the thermal conductivity, the viscosity of the resulting compositions undergoes a sharp increase and the handling and molding properties suffer from a substantial decline.
The object of this invention is to provide a thermoconductive silicone composition exhibiting good handling properties despite containing a large amount of thermoconductive filler in order to obtain a highly thermoconductive silicone composition.